P1129 Honda Code Meaning, Causes & Symptoms Explained

Honda vehicles are known for their reliability and longevity, but like any other vehicle, they can develop problems. One issue that Honda owners might encounter is the P1129 code. This code indicates a problem with the manifold absolute pressure (MAP) sensor circuit.

Any trouble with the oxygen sensor can cause P1129 to appear. When the engine is a closed loop, it means that it has sufficiently warmed up and is now adjusting its fuel delivery based on input from the oxygen sensor(s).

This is probably happening because a defective oxygen sensor is sending incorrect data to the computer, which prevents the engine from going into a closed loop.

An O2 sensor fault has been detected by the engine control computer and a P0052 has been triggered. In addition to the oxygen sensor issue, the engine cannot go into a closed loop, resulting in a P1129 error.

There is a connection between these two codes. It is likely that neither code will return after the P0052 is corrected and the engine codes are erased.

P1129 Honda Code: Manifold Absolute Pressure Sensor Circuit Higher Than Expected

The P1129 code is a diagnostic trouble code that indicates a fault in the MAP sensor circuit. The MAP sensor measures the pressure in the intake manifold and sends this information to the engine control module (ECM). If the ECM detects a problem with the MAP sensor circuit, it will set the P1129 code.

It generates a signal proportional to the amount of vacuum in the intake manifold that measures the Manifold’s Absolute Pressure. In order to control the air/fuel mixture ratio, the signal is sent to the Engine Control Module (ECM). 

P1129 Honda Code Symptoms 

1. Check Engine Light (CEL) illuminated on the dashboard: When the P1129 code is detected, the Check Engine Light will typically turn on. This is often the first indication that something is wrong with your vehicle, and it serves as a warning that you should have your Honda inspected by a professional.
2. Reduced engine power or acceleration: If the MAP sensor is not functioning properly, it may not provide the correct information to the engine control module (ECM). As a result, the ECM may not be able to adjust the air/fuel mixture or ignition timing as needed, which can result in reduced engine power and acceleration.
3. Poor fuel economy: When the engine is not running efficiently, it can lead to poor fuel economy. You may notice that you’re getting fewer miles per gallon than usual, which can be a frustrating and costly issue.
4. Engine stalling or hesitation: A faulty MAP sensor can cause the engine to stall or hesitate when you’re driving. This can be a dangerous situation, especially if it happens while you’re on the highway or in heavy traffic.
5. Rough idle: If the engine is not receiving the correct amount of air/fuel mixture, it may idle roughly or even stall. You may notice that the engine seems to be running unevenly or that it’s vibrating more than usual.
6. Difficulty starting the engine: If the MAP sensor is not providing the correct information to the ECM, it may be difficult to start the engine. You may need to turn the key multiple times before the engine finally starts.

It’s worth noting that not all of these symptoms may be present in every case of the P1129 code. 

Additionally, these symptoms can also be caused by other issues with your vehicle, so it’s important to have a professional diagnose the problem to ensure that it’s properly addressed.

Causes Of Honda P1129 Code

There are several possible causes of the P1129 code, including:

• A faulty MAP sensor
• A damaged or corroded MAP sensor connector
• A wiring issue in the MAP sensor circuit
• A failed ECM

Troubleshooting Honda P1129 Code

If you suspect that your Honda has a P1129 code, there are a few steps you can take to troubleshoot the problem. These might include:

• Checking the MAP sensor and its connector for damage or corrosion
• Inspecting the wiring in the MAP sensor circuit for breaks or damage
• Testing the MAP sensor using a multimeter or scan tool
• Checking the ECM for any faults or issues

How To Fix It?

The best way to fix the P1129 code is to diagnose and repair the underlying issue that is causing the code to be set. Here are some potential fixes depending on the root cause of the problem:

1. Replace the MAP sensor: If the MAP sensor is found to be faulty, it will need to be replaced. The sensor itself is typically not very expensive, and replacing it is a relatively straightforward process.
2. Repair or replace the MAP sensor connector: If the issue is with the connector for the MAP sensor, it may be possible to repair the connector or replace it entirely. A damaged or corroded connector can prevent the sensor from receiving the correct signals and cause the P1129 code to be set.
3. Repair wiring issues: If the wiring in the MAP sensor circuit is damaged or corroded, it will need to be repaired or replaced. This can be a more involved process, as it may require tracing the wiring throughout the vehicle to find the damaged area.
4. Replace the ECM: In rare cases, the ECM itself may be at fault, causing the P1129 code to be set. If this is the case, the ECM will need to be replaced. This is typically an expensive repair, as the ECM is a critical component of the vehicle’s electrical system.

Once the underlying issue has been addressed, the code can be cleared from the vehicle’s computer using a diagnostic tool. It’s important to note that simply clearing the code without addressing the underlying issue is not an effective fix, as the code will likely be set again in the future.

Diagnosing Honda P1129 Trouble Code 

To properly diagnose the P1129 code, it’s best to bring your Honda to a qualified mechanic or dealership. They can use specialized diagnostic equipment to pinpoint the problem and provide a fix.

Severity Of The Problem

The severity of the P1129 code depends on the underlying cause. If the issue is simply a damaged connector or wiring, it may be a relatively easy and inexpensive fix. However, if the problem is with the MAP sensor or ECM, it could be more serious and require more extensive repairs.

Conclusion 

If you notice any of the symptoms associated with the P1129 code, it’s important to have your Honda checked out by a professional. 

Ignoring the issue could lead to further damage and potentially expensive repairs down the line. With proper diagnosis and repair, however, you can get your Honda running smoothly once again.